The aims of the project are to solve the problems presented by the development of a radio amino assay for Vitamin A in biological material. It will be necessary to accomplish the following tasks: 1. Produce an antibody to Vitamin A of high affinity, so that radio amino assay will be sensitive to retinol in the peak-o-gram range. 2. Develop or adapt an extraction procedure in order to obtain Vitamin A from biological samples in a form suitable for a radio amino assay. 3. Develop a protocol for the radio amino assay of Vitamin A. 4. Apply the radio amino assay for Vitamin A to various biological and clinical materials.